The Toxicity, Pathophysiology, and Treatment of Acute Hydrazine Propellant Exposure: A Systematic Review.

INTRODUCTION: Hydrazines are highly toxic inorganic liquids that are used as propellants in military and aviation industries, such as the U.S. Air Force F-16 Emergency Power Unit and SpaceX SuperDraco Rockets. The most commonly used derivatives include hydrazine, monomethylhydrazine, and 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine). Industrial workers in close contact with hydrazines during routine maintenance tasks can be exposed to levels well above the National Institute for Occupational Safety and Health relative exposure limits. MATERIALS AND METHODS: A systematic review was performed using PubMed, Web of Science, Google Scholar, National Aeronautics and Space Administration Technical Server, and Defense Technical Information Center, and data related to hydrazine exposures were searched from inception to April 2020. Publications or reports addressing hydrazine toxicity, pathophysiology, and treatment of hydrazine fuel exposure were selected. RESULTS: Acute toxic exposures to hydrazine and its derivatives are rare. There are few case reports of acute toxic exposure in humans, and data are largely based on animal studies. The initial search identified 741 articles, manuscripts, and government reports. After screening for eligibility, 51 were included in this review. Eight articles reported acute exposures to hydrazine propellant in humans, and an additional 14 articles reported relevant animal data. CONCLUSIONS: Exposure to small amounts of hydrazine and its derivatives can cause significant soft tissue injury, pulmonary injury, seizures, coma, and death. Neurologic presentations can vary based on exposure compound and dose. Decontamination is critical as treatment is mainly supportive. High-dose intravenous pyridoxine has been suggested as treatment for hydrazine-related neurologic toxicity, but this recommendation is based on limited human data. Despite recent research efforts to generate less toxic alternatives to hydrazine fuel, it will likely continue to have a role in military and aviation industries. Aerospace and military physicians should be aware of the toxicity associated with hydrazine exposure and be prepared to treat hydrazine toxicity in at-risk populations.

Pharmacotherapeutic management of asthma in the elderly patient.

INTRODUCTION: Asthma is a heterogeneous syndrome with variable phenotypes. Reversible airway obstruction and airway hyper-responsiveness often with an atopic or eosinophilic component is common in the elderly asthmatic. Asthma chronic obstructive pulmonary disease overlap syndrome (ACOS), a combination of atopy-mediated airway hyper-responsiveness and a history of smoking or other environmental noxious exposures, can lead to some fixed airway obstruction and is also common in elderly patients. Little specific data exist for the treating the elderly asthmatic, thus requiring the clinician to extrapolate from general adult data and asthma treatment guidelines. AREAS COVERED: A stepwise approach to pharmacotherapy of the elderly patient with asthma and ACOS is offered and the literature supporting the use of each class of drugs reviewed. EXPERT OPINION: Inhaled, long-acting bronchodilators in combination with inhaled corticosteroids represent the backbone of treatment for the elderly patient with asthma or ACOS . Beyond these medications used as direct bronchodilators and topical anti-inflammatory agents, a stepwise approach to escalation of therapy includes multiple options such as oral leukotriene receptor antagonist or 5-lipoxygense inhibitor therapy, oral phosphodiesterase inhibitors, systemic corticosteroids, oral macrolide antibiotics and if evidence of eosinophilic/atopic component disease exists then modifying monoclonal antibody therapies.

The pharmacological management of asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS).

Introduction: Asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS) is a disease phenotype that shares T helper lymphocyte cell Th1/neutrophilic/non-Type-2 Inflammation pathways thought to be key in COPD and Th2/eosinophilic/Type-2 inflammatory pathways of asthma. The pharmacology of treating ACOS is challenging in severe circumstances.Areas covered: This review evaluates the stepwise treatment of ACOS using pharmacological treatments used in both COPD and asthma. The most common medications involve the same inhalers used to treat COPD and asthma patients. Advanced stepwise therapies for ACOS patients are based on patient characteristics and biomarkers. Very few clinical trials exist that focus specifically on ACOS patients.Expert opinion: After inhalers, advanced therapies including phosphodiesterase inhibitors, macrolides, N-acetylcysteine and statin therapy for those ACOS patients with a COPD appearance and exacerbations are available. In atopic ACOS patients with exacerbations, advanced asthma therapies (leukotriene receptor antagonists and synthesis blocking agents.) are used. ACOS patients with elevated blood eosinophil/IgE levels are considered for immunotherapy or therapeutic monoclonal antibodies blocking specific Th2/Type-2 interleukins or IgE. Symptom control, stabilization/improvement in pulmonary function and reduced exacerbations are the metrics of success. More pharmacological trials of ACOS patients are needed to better understand which patients benefit from specific treatments.Abbreviations: 5-LOi: 5-lipoxygenase inhibitor; ACOS: asthma - COPD overlap syndrome; B2AR: Beta2 adrenergic receptors; cAMP: cyclic adenosine monophosphate; cGMP: cyclic guanosine monophosphate; CI: confidence interval; COPD: chronic obstructive pulmonary disease; CRS : chronic rhinosinusitis; cys-LT: cysteinyl leukotrienes; DPI: dry powder inhaler; EMA: European Medicines Agency; FDA: US Food and Drug Administration; FDC: fixed-dose combination; FeNO: exhaled nitric oxide; FEV1: forced expiratory volume in one second; FVC: forced vital capacity; GM-CSF: granulocyte-macrophage colony-stimulating factor; ICS : inhaled corticosteroids; IL: interleukin; ILC2: Type 2 innate lymphoid cells; IP3: Inositol triphosphate; IRR: incidence rate ratio; KOLD: Korean Obstructive Lung Disease; LABA: long-acting B2 adrenergic receptor agonist; LAMA: long-acting muscarinic receptor antagonist; LRA: leukotriene receptor antagonist; LT: leukotrienes; MDI: metered-dose inhalers; MN: M-subtype muscarinic receptors; MRA: muscarinic receptor antagonist; NAC: N-acetylcysteine; NEB: nebulization; OR: odds ratio; PDE: phosphodiesterase; PEFR: peak expiratory flow rate; PGD2: prostaglandin D2; PRN: as needed; RR: risk ratio; SABA: short-acting B2 adrenergic receptor agonist; SAMA: short-acting muscarinic receptor antagonist; SDMI: spring-driven mist inhaler; Th1: T helper cell 1 lymphocyte; Th2: T helper cell 2 lymphocytes; TNF-α: tumor necrosis factor alpha; US : United States.

Massive diltiazem and metoprolol overdose rescued with extracorporeal life support.

The management of overdoses of cardioactive medications in the emergency department can be challenging. The reversal of severe toxicity from one or more types of cardioactive medication may fail maximal medical therapies and require extreme invasive measures such as transvenous cardiac pacing and extracorporeal life support. We present a case of massive diltiazem and metoprolol overdose refractory to maximal medical therapy, including intravenous calcium, glucagon, vasopressors, high dose insulin, and lipid emulsion. The patient experienced refractory bradydysrhythmia that responded only to transvenous pacing. Extracorporeal life support was initiated and resulted in successful organ perfusion and complete recovery of the patient. This case highlights the potential utility of extracorporeal life support in cases of severe toxicity due to multiple cardioactive medications.

Muscarinic antagonists in early stage clinical development for the treatment of asthma.

INTRODUCTION: Parasympathetic neurons utilize the neurotransmitter acetylcholine to modulate and constrict airway smooth muscles at the muscarinic acetylcholine receptor. Inhaled agents that antagonize the muscarinic (M) acetylcholine receptor, particularly airway M3 receptors, have increasing data supporting use in persistent asthma. Areas covered: Use of inhaled long-acting muscarinic antagonists (LAMA) in asthma is explored. The LAMA tiotropium is approved for maintenance in symptomatic asthma patients despite the use of inhaled corticosteroids (ICS), leukotriene receptor antagonists (LTRA) and/or long-acting beta2 agonists (LABA). LAMA agents currently approved for chronic obstructive pulmonary disease (COPD) include tiotropium, glycopyrrolate/glycopyrronium, umeclidinium and aclidinium. These agents are reviewed for their pharmacological differences and clinical trials in asthma. Expert opinion: Current guidelines place inhaled LAMAs as adjunctive maintenance therapy in symptomatic asthma not controlled by an ICS and/or a LTRA. LAMA agents will play an increasing role in moderate to severe symptomatic asthma patients. Additional LAMA agents are likely to seek a maintenance indication perhaps as a combined inhaler with an ICS or with an ICS and a LABA. These fixed-dose combination inhalers are being tested in COPD and asthma patients. Once-a-day dosing of inhaled LAMA agents in severe asthma patients will likely become the future standard.

The Changing Drug Culture: Medical and Recreational Marijuana.

The major psychoactive compounds in marijuana (cannabis) are cannabinoids, the most significant of which is delta-9-tetrahydrocannabinol. There are also two synthetic pharmaceutical cannabinoids, nabilone and dronabinol, available by prescription in the United States. The use of marijuana has increased in the United States with passage of medical marijuana laws in many states and legalization of recreational marijuana use in several states. In addition, the potency of marijuana has increased in recent years. Marijuana has been used for a variety of medical purposes, including management of nausea and vomiting, appetite and immunologic stimulation in patients with HIV infection and AIDS, glaucoma, neurologic disorders, and pain relief. Studies on the benefits of marijuana as a treatment for various conditions have been inconsistent, except for those on pain management. Marijuana has adverse effects, and has been associated with driving impairment, psychosis, dependence and withdrawal syndromes, hyperemesis, acute cardiac events, some cancers, and impaired lung function. As with studies on the benefits of marijuana, studies of adverse effects have yielded inconsistent results. Except for impaired driving and the occurrence of dependence and withdrawal syndromes, the adverse effects of marijuana use have not been fully studied.

The Changing Drug Culture: Use and Misuse of Cognition-Enhancing Drugs.

There has been an increase in diagnoses of attention-deficit/hyperactivity disorder (ADHD), with approximately 9% of American children now diagnosed, and a concomitant increase in the use of stimulants (eg, amphetamines, methylphenidate) to manage ADHD. Nonstimulant drugs (eg, atomoxetine, guanfacine, clonidine) also are used, but most patients are treated with stimulants. All of these drugs are effective for management of ADHD, and, overall, use in childhood does not seem to increase the risk of substance abuse later in life. However, widespread use has resulted in prescription stimulants being diverted for nonmedical uses, particularly by high school and college students seeking cognitive enhancement for improved academic performance. Studies of ADHD drugs for improving cognition in patients without ADHD have mixed results, and any improvements appear to be modest and short-term. Other substances also are used for cognitive enhancement. Drugs for Alzheimer disease are being used for mild cognitive impairment, though there is no evidence that they are effective. Creatine may have mild cognition-enhancing properties, but study results often are confounded by the addition of exercise, which by itself is thought to improve cognition. There is no evidence that other supplements, such as vitamins and omega-3 fatty acids, improve cognitive function.